Scomber colias is one of the most important commercial species throughout its habitat. It is fished mainly on the eastern side of the Atlantic (Bay of Biscay to South Africa) as well as in the Mediterranean, mostly in purse seine and pelagic trawl fisheries which target Sardina pilchardus and/or Engraulis engrasicolus. Often being bycatch (and then slipped), it may become the target species when it is highly available whereas sardine and anchovy are not. Another reason contributing to the recent rise in landings is the appearance of new markets (e.g., for tuna feeding). Tuna are among the natural predators together with swordfish, sharks, dolphins, and seals, so these risk becoming bycatch themselves when they are accidentally engulfed by the purse seine – just as other pelagic and semi- pelagic species may be accidentally caught.
The medium-sized pelagic S. colias may already suffer from injuries and stress when the purse seine is hauled close to the ship. Whether slipping of unwanted catch results in delayed mortality requires further research; discarding – once on board – is mostly done when the IND are dead and so should be avoided. Transfer to the storage space via scoop net potentially objects wanted S. colias to further crowding, contact with the gear, lack of oxygen, and experience of its own weight. Storing most likely happens alive and without or with only little ice. And since death occurs most likely through asphyxia, the best would be pumping the IND on board and then immediately stun them followed by slaughter while still unconscious. Further research is needed for such a protocol.
